How much protein you need per kilogram, for muscle gain and for fat loss

Why protein targets are set per kilogram, not as a flat number

Protein needs scale with body size and how much muscle tissue you're asking your body to build or preserve, which is why every serious recommendation is expressed in grams per kilogram of bodyweight rather than a single number for everyone. A 55 kg person and a 100 kg person training the same program don't need the same 150 g/day — they need roughly the same per-kilogram target, scaled to their own size.

What the research actually found

The most directly relevant evidence is a 2018 systematic review, meta-analysis and meta-regression by Morton and colleagues in the British Journal of Sports Medicine, pooling data from resistance-trained adults across many studies (PubMed). It found that protein intake up to roughly 1.6 g/kg/day continued to improve gains in muscle mass and strength from resistance training, with intakes above that point producing little additional measurable benefit on average — a useful threshold, though the analysis also noted individual variation around it.

The International Society of Sports Nutrition's 2017 position stand on protein and exercise, led by Jäger and colleagues, sets a broader working range: roughly 1.4–2.0 g/kg/day is sufficient for most people trying to build or maintain muscle through resistance or endurance training, with higher intakes (2.3–3.1 g/kg/day) potentially useful for preserving lean mass specifically during a calorie deficit, since dieting itself increases the protein needed to prevent muscle loss (full position stand, PMC). That higher range during a cut is the key detail most general advice leaves out: your protein target should go up, not stay flat, when your calories go down.

Worked example: three goals, one bodyweight

Take an 80 kg person training with weights:

• General health / sedentary baseline (~0.9 g/kg): 80 × 0.9 ≈ 72 g/day
• Muscle gain (~1.8 g/kg, inside the ISSN's 1.4–2.0 g/kg range and above Morton's ~1.6 g/kg threshold): 80 × 1.8 = 144 g/day
• Fat loss while preserving muscle (~2.2 g/kg, reflecting the higher end used during a deficit): 80 × 2.2 = 176 g/day

At 4 kcal per gram, that 176 g/day fat-loss target is 704 kcal from protein alone — worth accounting for directly when setting a calorie deficit, since it changes how much room is left for carbs and fat in the rest of the day.

Is more protein ever better?

Past roughly 2.2 g/kg/day, Morton's meta-analysis and the broader literature it draws on find little additional benefit for muscle growth in most people — the dose-response curve flattens. The ISSN position stand does note emerging evidence that intakes above 3.0 g/kg/day may help with fat loss specifically in resistance-trained individuals, likely through protein's higher satiety and metabolic cost relative to carbs or fat, but that's a different goal than maximizing muscle gain, and it's a smaller, newer body of evidence than the 1.6 g/kg threshold. There is no established evidence of harm from these intakes to people with healthy kidney function; the caveat that matters is for anyone with existing kidney disease, who should get an individualized target from their physician rather than using a general-population range.

Spreading protein across the day

Research summarized in the ISSN position stand suggests roughly 0.25 g/kg (or about 20–40 g) of high-quality protein per meal, spread across 3–5 meals, helps maximize muscle protein synthesis compared to the same total eaten in one or two large meals. This is a secondary detail, though — total daily intake matters far more than exact timing or meal count. If hitting your daily gram target in three meals is more realistic for your schedule than forcing five, the three-meal version with a similar total will get you most of the same benefit.

Does protein source matter?

The g/kg targets above assume "high-quality" protein — sources that supply a full spread of essential amino acids in reasonable proportions, such as meat, fish, eggs, dairy and soy. The ISSN position stand specifically calls out leucine content as a driver of muscle protein synthesis, recommending roughly 700–3,000 mg of leucine per dose alongside a balanced amino acid profile; most animal proteins and soy hit that easily in a normal serving, while single plant sources (rice or pea protein alone, for instance) may need larger portions or a mix of sources to match it. This matters more for hitting per-meal thresholds efficiently than for the daily total — someone eating primarily plant protein can still reach the same g/kg target, it may just take a slightly larger volume of food or a wider variety of sources to do it well.

Turning this into a plan

Start from your current bodyweight, not a goal weight, and pick the per-kilogram target that matches what you're actually doing: closer to 1.6–1.8 g/kg if the goal is building muscle at maintenance or a slight surplus, closer to 2.0–2.2 g/kg if you're in a calorie deficit and want to protect lean mass while losing fat. From there, the protein intake calculator on this site turns your bodyweight and goal into a daily gram target and a rough per-meal split, and the macro calculator can slot that protein target into a full breakdown alongside carbs and fat once you've also set a calorie target with the calorie deficit calculator.

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This article summarizes published sports nutrition research and is general information, not individual medical or dietary advice. People with kidney disease or other medical conditions should get a personalized protein target from a doctor or registered dietitian.